1. Field of the Invention
The invention relates to a vehicle performance inspection apparatus and a vehicle performance inspection method, and more particularly to a vehicle performance inspection apparatus and a vehicle performance inspection method wherein the operational state and the performance of the function of the ABS (anti-lock brake system) in a vehicle are evaluated and when the operational state and the performance of the LSD (limited slip differential) function and the TRC (traction control) function are evaluated, the arrangements are correspondingly changed and sectioned for evaluation and when the operational state and the performance of the ABS function, the LSD function, and the TRC function are evaluated, the arrangements are correspondingly and mutually changed and sectioned for evaluation.
2. Prior Art
Conventionally, the ABS control in a vehicle is well known as a function for securing favorably and effectively the running stability and the steerability at the time of abrupt braking operation by controlling the braking force correspondingly to the degree of the lock of each of the front and rear wheels at the time of the abrupt braking operation to prevent the running direction of the vehicle from inadvertently deviating due to the locked state of the wheels.
The LSD control in a vehicle is well known as a function for securing favorably and effectively the running stability and the steerability at the time of deviated operation by distributing, in a so-called differential mechanism for absorbing the difference between rotations of the left and right wheels at the time of deviated operation of the running direction of the vehicle, the rotational driving torque optimally to each of the left and right wheels correspondingly to the difference between rotations of the left and right wheels.
Further, the TRC control in a vehicle is well known as a function for securing favorably and effectively the running stability and the runnability at the time of starting and quick acceleration. By controlling optimally the rotational driving force to be transmitted to the left and right driving wheels from the mounted engine correspondingly to the conditions of the running surfaces the TRC restrains the spinning of the left and right driving wheels which is liable to occur at the time of the starting or quick acceleration.
That is, out of the above functions, for example, the ABS function works by constitution composed of a computer as a main control device, wheel speed detecting means of detecting the wheel speeds of front left and right and rear left and right wheels and outputting wheel speed signals, and oil pressure supply control means of controlling the oil pressure forces to respective braking cylinders for the left and right wheels based on the selected control signals from the computer.
From the computer, based on the wheel speed signals outputted from the wheel speed detecting means, selected control signals for obtaining adequate braking forces corresponding to the speed of the vehicle and the conditions of the running surfaces are outputted to the oil pressure supply control means to adjust the mode of the oil pressure supply control means so that when the wheel speed RS has been decreased greatly in comparison to the vehicle speed CS (when the particular wheel has come near to the locked state), the oil pressure supplied to the braking cylinder for the particular wheel may be decreased to reduce the braking force whereas when the wheel speed RS has come near to the vehicle speed CS, the oil pressure supplied to the braking cylinder for the particular wheel may be increased to enhance the braking force and these operations may be repeated to allow desired optimum braking operation even at the time of abrupt braking operation.
Therefore, it is considered that vehicles fitted with the above ABS function will become popular in the future quickly and accordingly development of a performance inspection apparatus for evaluating quickly and easily whether an ABS function built in a vehicle operates normally and smoothly at all times, that is, development of an ABS performance inspection apparatus is desired strongly. The desire of development is also present for a performance inspection apparatus for vehicles fitted with the above LSD function and TRC function, which are not described herein because their constitution is well known.
A conventional typical simulating ABS performance inspection apparatus is suggested, for example, in Japanese Patent Application No. Sho 62-304577 and the constitution thereof is shown schematically in FIG. 10.
That is, the constitution of the suggested ABS performance inspection apparatus shown in FIG. 10 is such that pairs of parallel receptive support rollers 1 and 2 which are arranged rotatably and positioned to correspond to the front left and right wheels and rear left and right wheels of a vehicle, the front left and right wheels and rear left and right wheels 3 of the vehicle whose performance is to be inspected are received and supported orthogonally on the receptive support rollers 1 and 2, a motor 4 is connected to one side of one of the paired receptive support rollers 1 and 2, for example, one side of the receptive support roller 1 so that that receptive support roller 1 may act as a driving receptive support roller and the other receptive support roll 2 may act as a driven receptive support roller, torque detection means (for example, a torque meter) is situated between one side of said particular driving receptive roller and the motor 4, and rotational frequency detection means (for example, a pulse meter) 5 is situated on the other side.
Thus, in the suggested ABS performance inspection apparatus having the above constitution, the front or rear left and right wheels of a vehicle whose performance is to be inspected are received and supported orthogonally on the pairs of the receptive support rollers 1 and 2, then the driving receptive support rollers 1 are rotatably driven by the motors 4 so that the received and supported particular wheels 3 may be rotated, for example, at a speed of about 30 to 60 km/h under the control of the rotational frequency detection means 5, and after the rotational speed is bought to the steady state, with the driven rotational state of the driving receptive support rollers 1 being kept, the braking action on the left and right wheels 3, that is, the braking operation is started from inside the vehicle.
With the start of the above braking action the driving torques or the load changes produced between the driving receptive support rollers 1 and the wheels 3 and also between the receptive support rollers 1 and 2 and the wheels 3 are detected by the torque detection means 6, and in this case since the torque values detected by the torque detection means 6 correspond approximately to the load resistances between the wheels and a running surface, an inspection by simulating the desired ABS control becomes possible for a vehicle whose performance is to be inspected.
In this case, since, in particular, the measurement is possible with the driving receptive support rollers 1 being rotationally driven, in other words, with the subject vehicle receiving load resistances all the time from the receptive support rollers 1 and 2 which simulate actual running surfaces, the inspection of the braking performance can be effected in a state approximating the actual road surface situations.
On the other hand, since the driving receptive support rollers 1 are driven to rotate and after the wheels 3 of the vehicle received and supported on the receptive support rollers 1 and 2 are brought to a steady rotational speed, a prescribed braking action is started, the load resistance between the particular driving receptive support rollers 1 and the wheels 3 do not change and therefore the state of the braking action by the ABS function can be easily grasped for actual road surface situations.
If the above suggested ABS performance inspection apparatus is studied in detail, in the case where, in this performance inspection apparatus, the weight of the vehicle whose performance is to be inspected including the load on the vehicle is proportioned to the weight of the pairs of the receptive support rollers substantially supporting that weight, in other words, they are in accord with each other, the inspection of the ABS control for actual road surface situations by simulation is possible as is shown by a curve (a) in FIG. 3 described later, and no particular fear of a problem arises if the ABS performance inspection apparatus is applied to special types of vehicles whose weight is nearly constant at all times such as passenger cars.
However, if the weight of the subject vehicle and the weight of the driving receptive support rollers are not proportioned to each other and only the weight of the vehicle is increased relatively, the weights of them are not in accord with each other and, as is shown by a curve (c) in FIG. 3, when a braking action is taken from inside the vehicle, then the rotational driving forces of the driving receptive support rollers by the motors are excessively suppressed and the vehicle speed drops sharply, thereby leading to a state wherein the ABS control cannot be carried out, whereas if the weight of the vehicle is decreased relatively, as is shown in by a curve (b) in FIG. 3, when a braking action is taken from inside the vehicle, the rotational driving forces by the motors are not correspondingly suppressed sufficiently, and the ABS control is not necessarily worked favorably.
Accordingly, in the case of the suggested ABS performance inspection apparatus, although it is effective when it is applied to the performance inspection of the ABS function of the same kind of vehicles whose weights are approximately the same, there is a problem that it cannot always be applied in general to vehicles whose weights are varied.
Although performance inspection apparatuses for the above LSD function and TRC function are not described herein, proper performance inspection apparatuses that work for these functions respectively are not found now and development of performance inspection apparatuses for the LSD function and the TRC function is still demanded strongly.